| Radioactive strontium pollution problems exist in parts of northwest China. For the purpose of controlling radioactive strontium (90sr) contaminated soil, the stable isotopes of strontium-88were adopted to simulate radioactive isotopes of strontium-90,26cultivar species (6wheat varieties,4barley varieties,8husk oats varieties and8naked oats varieties) were chosen as experimental material, the combination of sand pot experiment and soil culture pot experiment were carried out to research strontium on the absorption, distribution, transportation and accumulation patterns in wheat, oat and barley crops. This article is supposed to select species which has such advantages as high concentration, big bio mass, adapt to the local ecological conditions. This work is ready for the early work for phytoremediation of nuclide contaminated soil.The main results were as follows:1.2008-2009, sand pot experiment was carried out to investigate the enrichment characteristics of strontium and strontium distribution patterns in different organs of26varieties of wheat and barley crops (6wheat varieties,4barley varieties,8husk oats varieties and8naked oats varieties). The results showed that strontium had no significant impact on crop biomass. Compared strontium enrichment concentration between different crop varieties, the highest was naked oats, followed by barley, husk oats, minimum was wheat. Compared strontium concentration in different organs of same crop varieties, roots of barley was the highest, while leaf of wheat, oats and naked oats was the highest. Compared transfer coefficient (TLFs) in different crops, in100mgkg-1Sr treatment, naked oats was the highest (0.653～1.959), followed by skin oats (0.480～1.476), wheat (0.474～0.824) and barley (0.286～0.574). In500mgkg-1Sr treatment, naked oats was the highest (1.041～2.741), followed by skin oats (0.396～1.890), wheat (0.223～0.804) and barley (0.303～0.798). Phytoremediation materials can be chosen in naked oats. Among them, the Inner Mongolia technical arts (1naked oats) the floor of the enrichment of strontium concentration and root cap transfer coefficient in26varieties of wheat and barley crops are the highest. At100and500mgkg-1Sr treatments, strontium enrichment concentration of Neimengkeyi-1(naked oats) was2213mgkg-1and7865mgkg-1respectively, TLF was1.959and2.741, respectively. Neimengkeyi-1(naked oats) has the characteristics of hyperaccumulator (TLF>1), showed strong ability of strontium concentration, and was recommendable as potential strontium contaminated soil materials for phytoremediation. Strontium concentration and translocation factor in wheat varieties was the lowest, showed the characteristics of metal excluding plants, and could be used as edible crops grown in strontium lightly polluted areas.2. In2009-2010, this experiment compared the plant growth and physiological response of antioxidant enzyme system of two naked oat genotypes (Bayu-3and Neimengkeyi-1) at seedling stage in sand pot experiment. The results showed that:(1) strontium addition significantly reduced the bio mass of Bayou-3, including the ground bio mass (16%), root biomass(18%), root length (26%) and the root area (23%). Low concentration of strontium addition did not reduce Neimengkeyi-1biomass. Neimengkeyi-1aboveground biomass decreased under high concentration strontium treatment, but higher than control by11%.(2) The strontium enrichment concentration in roots and leaves increased with increased addition of strontium concentration. Strontium enrichment concentration of Neimengkeyi-1at low concentration of strontium treatments (0.15and0.15mM Sr) was close to or higher than the Bayou-3. And under the high concentration of strontium treatments (3and6mM Sr), strontium enrichment concentration of Neimengkeyi-1was significantly higher than Bayou-3(about2times higher).(3) TLFs first rose than dropped with the increase of strontium concentration treatments. The TLFs of Neimengkeyi-1(1.66～2.03) were higher than the TLFs of Bayou-3(0.87～0.87) in all strontium addition treatments.(4) The strategies of Leaves and roots responding differently to strontium treatments induced oxidative stress response. Leaf MDA content was below the root, leaf SOD and POD activity was higher than the root.(5) MDA content in the leaves and roots of Neimengkeyi-1was below the Bayou-3, SOD, POD and CAT activity in leaves and roots of Neimengleyi-1of is higher than Bayou-3. The all results showed that the antioxidant defense system within the plant to responding the strontium stress in naked oats differently between genotypes. The different ability of naked oat genotypes responding to metal strontium stress possibly originated from its internal antioxidant system to cope with strontium pressure stress.3. In2010-2011, the four naked oats varieties (Bayou-3, Mengmai-8313, Dingyou-6and Neimengkeyimai-1) were chosen in soil culture pot experiment. This experiment investigated metal strontium concentration distribution and enrichment in different organs in harvest between different crop varieties, we found that mature oats had higher strontium enrichment ability, strontium metal were mainly distributed in leaf and stem; Under the treatment of different concentrations of strontium stress, the concentration of the leaves was the highest, the concentration of the grain was the lowest; Under different concentration of strontium stress treatment, Neimengkeyimai-1above strontium enrichent concentration was the highest of four genotypes. Neimengkeyimai-1can be used as a kind of effective ideal phytoremediation plant for strontium pollution. In addition, this experiment compared the soil enzyme activity (dehydrogenase, β-glycosidase, urease, acid phosphatase and alkaline phosphatase) and microbial biomass carbon and nitrogen. Urease, MBC and MBN were sensitive to soil strontium pollution.In summary, phytoremediation materials can be choose in naked oats varieties. Strontium concentration of wheat was the lowest, translocation coefficient of wheat was the lowest, and wheat can be considered as food-grade crop varieties in low-dose strontium metal pollution area. Urease, MBC and MBN was sensitive to soil pollution of strontium. Shoot Sr enrichment concentration of Neimengkeyimai-1was the highest. Neimengkeyimai-1can be used as an effective ideal phytoremediation plant. Our results prepared for remediation of strontium nuclides polluted farmland. |
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